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Spintronics of helical edge states interacting with a quantum magnet

与量子磁体相互作用的螺旋边缘态的自旋电子学

基本信息

批准号：
392402582
负责人：
Professor Dr. Piet W. Brouwer
金额：
--
依托单位：
Institut für Theoretische Physik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/392402582?language=en
关键词：
Spintronics helical edge states interacting

项目摘要

The existence of helical edge states is a key feature of a two-dimensional topological insulator. These edge states are immune against single-particle backscattering in the absence oftime-reversal symmetry breaking felds. Placing a magnetic insulator in proximity to the helical edge states, the Exchange field will open a gap in the helical edge state spectrum.Surprisingly, when the magnet has its own dynamics with a properly aligned easy-plane anisotropy, the application of a voltage bias sets the magnet in a precessional mode in which the magnet pumps charge in such a way that the quantized quantum spin Hallconductance is restored, in spite of the presence of a gap in the excitation spectrum of the helical edge. This leads to intriguing transport and noise properties, and was proposed to bea platform for the realization of an adiabatic quantum motor.Building on our previous joint work [Silvestrov, Recher, and Brouwer, Phys. Rev. B 93, 205130 (2016)], we here propose to extend the study of this remarkable system into new directions,such as thermoelectric effects, and consider aspects beyond the idealized model description used in previous publications by us and others. Specifically, in a first set of subprojects we address thermoelectric applications of an easy-plane magnetic insulator exchange-coupled to a helical edge, and device applications such as "thermomagnetization", a "thermal quantum Motor", and a mesoscopic "electron cooler". Other directions of research here include nonlinear transport, low frequency noise and magnetization fluctuations as well as quantum interference effects. The second half of the proposal will be devoted to generalizations of theidealized model. We plan to use the Landau-Lifshitz equation for the description of the current/bias driven dynamics of a Setup with less symmetries than in the original publications. New interesting features in current-voltage characteristics and magnetization dynamics are expected. Other proposed Problems include the case of a magnet with several degrees of freedom and a metallic magnet.

螺旋边缘态的存在是二维拓扑绝缘子的一个重要特征。在没有时间反转对称性破缺场的情况下，这些边缘态不受单粒子后向散射的影响。在螺旋边缘态附近放置一个磁性绝缘体，交换场将在螺旋边缘态光谱中打开一个间隙。令人惊讶的是，当磁铁具有适当排列的易平面各向异性时，施加电压偏置使磁铁处于进动模式，在进动模式中，磁铁以这样一种方式泵出电荷，从而恢复量子化的量子自旋霍尔电导，尽管在螺旋边缘的激发谱中存在间隙。这导致了有趣的传输和噪声特性，并被提出作为实现绝热量子电机的平台。基于我们之前的联合研究[Silvestrov， Recher, and browwer, Phys]。Rev. B 93, 205130(2016)]，我们在此建议将这一非凡系统的研究扩展到新的方向，例如热电效应，并考虑超出我们和其他人在先前出版物中使用的理想化模型描述的方面。具体来说，在第一组子项目中，我们将讨论易平面磁性绝缘体交换耦合到螺旋边缘的热电应用，以及诸如“热磁化”，“热量子马达”和介观“电子冷却器”等设备应用。其他研究方向包括非线性输运、低频噪声和磁化涨落以及量子干涉效应。提案的后半部分将致力于理想化模型的概括。我们计划使用Landau-Lifshitz方程来描述比原始出版物中更少对称性的装置的电流/偏置驱动动力学。期望在电流-电压特性和磁化动力学方面有新的有趣的特性。其他提出的问题包括具有几个自由度的磁体和金属磁体的情况。